The Sand River is the lifeblood of the Sabi Sand Game Reserve, bringing an endless supply of water to the animals within it. At Londolozi, we are fortunate enough to have it flowing right through the heart of the property. It is because of this, along with the abundance of deep pools found along the river that we have a very healthy population of hippos, calling Londolozi home. The high density of hippos means that they are a regular feature during game drives and further prompts the guest to question
“Can hippos swim?”
In short, the answer is,
But it’s not that simple.
Let us dive a little deeper into this to explain why not, pun intended.
Hippos have highly sensitive skin
That dehydrates at a rapid rate if exposed to the sun for long periods of time. Because of this, hippos are water-bound and spend the majority of the day submerged, with maybe just the tops of their heads above the water. Therefore hippos are mostly viewed while they are in the water and are seen moving around in the water, so it is a valid question.
Hippos have extraordinarily dense bones
Essentially hippos are bottom dwellers, this means they rather walk on the bottom of watering holes or rivers and have a unique way of using buoyancy to do so. Parts of the hippo’s skeleton have very dense bones due to the replacement of porous bone with more compact bone. This means that their bones act as a kind of ballast to help them achieve neutral buoyancy underwater. Since they do not have to actively hold themselves down, and the watery environment buoys them up, they can walk, prance, and even “fly” underwater. Over and above this they are able to further regulate their buoyancy by controlling their breath. Creating a negative buoyancy by breathing out allowing them to sink quicker.
Coming up for air
Once under the surface, essentially holding their breath, they will be able to walk around for roughly five minutes before having to come up for air.
This is done in one of three ways:
- Simply walking to a shallower point in the water source when they can remain standing with just their heads sticking out the water,
- By standing on their back legs and pushing their head up towards the surface,
- By launching themselves from the bottom up to the surface, filling their lungs before slowly sinking back down. pushing their way to the surface in deeper water taking a breath and slowly return to the bottom, this is in fact not swimming as they can’t propel themselves along the surface while doing this.
Since they can’t swim, but rather walk on the bottom of rivers they play a vital role in keeping slow-moving waterways open with their own movements, maintaining channels, minimizing the effects of siltation and vegetation growth allowing water to flow through these paths.
Hippos play a major role in maintaining river courses throughout Africa, something that has always amazed me. One can only imagine what our rivers would look like without them. Certainly, the Sand River that is a perennial river, would probably not be as mighty if it wasn’t for the hippos that are constantly moving around it allowing the water to flow all year round.
Next time when wondering if a hippo can swim or not, remember that due to the fact that they can’t, many rivers around Africa probably wouldn’t have the luxury of having flowing water all year round.